The present invention relates to a method for treating a fluid, in particular a beverage, more specifically beer.
Fluids, including beverages are treated for numerous purposes. During the manufacturing of beverages like beer, wine or fruit juices a so called stabilization process is needed which at least substantially reduces the amount of components in the fluid which might give rise to flocculation or development of haze during storage and transportation of the fluid. Filtration and adsorption are the most important mechanisms used to this end. Other fluids need treatment with respect to, e.g., removal of suspended solids, others are to be subjected to chemical reactions.
Frequently, layers of deposited particulate material are used to perform such treatments, such layers may be used in the form of a filter cake.
EP 0 645 446 A1 suggests to deposit the particulate material in a cartridge on a fluid-permeable wall portion, said cartridge including a fluid inlet upstream of the deposited layer and a fluid outlet downstream of said fluid-permeable wall portion.
Cartridges of such design are widely used in the treatment of fluids, especially beverages, on an industrial scale since the cartridges can easily be designed to accommodate larger quantities of particulate material and are simple to handle.
During the treatment of the fluids the fluid is forced to pass through the deposited layer by a fluid pressure. Because of various technical reasons the fluid pressure cannot be kept constant but rather pressure fluctuations are frequently observed.
Numerous useful particulate materials form deposited layers which may crack under various conditions, e.g., the above mentioned pressure fluctuations, temperature changes or other physical or chemical impacts creating gaps leading from the upstream to the downstream side of the deposited layer. As a consequence a homogeneous fluid flow through the deposited layer is no longer guaranteed affecting the quality of the treated fluid.
In order to cope with this problem the deposited layer will have to be replaced frequently in order to ensure reliable quality of the treated fluid. The particulate material however has not been exhausted in its treatment capacity.
Some of the desirable particulate materials, like PVPP (polyvinyl polypyrrolidone) are not suitable for use in such cartridges at all and can be used as a stabilizing agent only in so-called dosing systems, where the PVPP particles are fed into the fluid and have to be removed subsequently by filtration. The loss of PVPP particles is substantial in such a procedure.